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Discussion Starter #1
Hi can someone please help me with the following problem.My 2001 ml320 just shut down while it was moving and running without any warning. While I was waiting for tow ,I tried to turn it on couple of times and it wouldn't even crank motor. What I did notice that headlight turn on and radio turns on with key in off position .Everything else didn't turn on ,like power locks and dome light and flashers. When i turn key to first and second position the following only worked the radio,two warning lights airbags off and srs ,the time ,temp and odometer but not the transmission selector indicator symbol and wipers worked.The things that didn't work were the following power windows, door lock, gauges,power seats,turn signals ,brakelights ,fan and ac. I then tried to crank motor and motor won't crank. When i got home I charged Battery and check voltage reading of 12.67 volts with ignition key to off position and with key in second position 12.42 volts.I also cleaned battery terminals and cables and ground on firewall.I recheck car again and the things i mention above with key off were still the same. I then turn key to second position and same thing that I mention above were the same no change. I then tried to crank motor and still no cranking.I then checked the fuse/relay box in engine compartment .I checked the starter relay #K8 first,I swap it out and no change,I then remove relay .Then with ignition key in off position i jump terminals # 30 and #87 and motor cranked. Next i checked circuit 15 # 12 relay and swap it out and no change.I then pulled relay to test terminals and found following #30 terminal with key in off and second position 12.57 volts. With key in second position i check terminal #85 and got 0 volts.Then with key still in second position I checked terminal #86 by doing the following ,i connected my voltage meter positive side to positive side of battery and then neg.side to terminal 86 and 0 volts.I then checked the fuse/relay box on inside of car located on front passenger right kick panel.Circuit 15 relay # K9 and fuse # f26 70 amp work and have power when key is in second position.I then checked ignition switch with key off first and red wire has 12 volts and with key in second position pink wire has 12 volts.I then connected a code reader with key in second position and it read "link error", so I couldn't pull any codes. Does anybody have any suggestions.Thanks
 

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2015 ML250 Bluetec and 1987 560SL
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If your ML320 is like my 2001 E320 wagon was, it won't even attempt to crank the engine if the battery power is too low. Your symptoms sure sound like a low battery.

Have you tried a jump start?

Also, your vehicle is a W163, not a W164. You're much more likely to get answers in the W163 forum.
 

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Discussion Starter #3
Hi Jaymaynard
Thanks for your response. I did recharge battery and checked it with a multimeter and it read 12.67 volts. I then boost it with a battery charger and I tried to start it and nothing happened ,not even dome light turned on. Is 12.67 volts not enough to power starting system or done lights etc. I did remove the starter relay #K8 located in relay/fuse box and swap it out and nothing changed.I then removed the relay again and with key in off position ,I jump terminals #30 and #87 and motor crank.Thanks for your advice .I will post it in the W163.
 

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2000 ML55 sold? 2013 ML500,? 2015 C250 estate wagon, 1927 Dodge 4 sedan, 1929 Dodge
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Sounds like a flat battery. It has a low voltage reading after being charged, get it load tested and see how it goes. It should be minimum 12.8v after a charge. Once you get the engine running check also that your alternator is working. It should read up around 14v at the battery when charging.
 

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Discussion Starter #5
Hi mattml430
I just had battery test done at parts store where i originally bought it.They say battery is in good condition ,no shorts ,starting load good and fully charged.Thanks
 

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2000 ML55 sold? 2013 ML500,? 2015 C250 estate wagon, 1927 Dodge 4 sedan, 1929 Dodge
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I would go through and clean all the terminal connections from the battery to the starter. Behind the batt on the firewall and check the earth straps. I know you said you've done the batt terminals but go through them all.
 

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ML 270CDI 2002, BMW K1300S, VW POLO 1.9TDI
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I would go through and clean all the terminal connections from the battery to the starter. Behind the batt on the firewall and check the earth straps. I know you said you've done the batt terminals but go through them all.
As above, particularly check the earth lead from the engine to the chassis.........an easy way to confirm if its an earth problem is to connect a jump lead from the negative pole of the battery directly to the engine block.
 

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2002 ML320, 2003 A160, 2002 ML500, 2018 GLS350d
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If the engine cranks when you bypass the starter relay k8, then you know that your battery and connections are OK. (So you don't need to check them again.)

I think you are on the right track with investigations into circuit 15. If you've proved that the ignition switch is working and the relay is good, then you are down to the AAM and the wiring. If you read about previous cases, when it's not the ignition switch, it's usually the AAM.

Re: the relay k12 terminals in the fuse box, you need to confirm that #86 is at ground or B negative. It should not be +12 V (or 0 volts relative to B positive as you described).
 

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It does seem that you have a cir. 15 problem and it is probably going to be an AAM issue.

Turn the key to pos. #2 and check for B+ at the cir. 15 stud on the fuse box. If not.............

Since you are getting B+ at the Ign. Sw. PINK wire, it is not an Ign. Sw. (S2) problem. Look at the diagram and you will see that the PINK wire goes directly to conn. C/D pos. #6 at the fuse box and then into the AAM by pin #1 .

Then it travels through an NPN resistor and out of the AAM through pin #2 7 and then to slot 85 of the K12 relay. DrX said it was slot 86 but it was probably a typo.

So to make sure that there is no wiring problem, remove both covers to the fuse box, and with the key in pos. #2 check for GROUND at the 31 stud and B+ and the cir. 15 stud. If there is no voltage at the cir. 15 stud, then...........

Remove the 3 screws and pull the fuse/relay module out of the box and turn it over onto a folded towel and locate conn. C/D wire #6 PINK and test for B+. If there is no B+ then it is a wiring problem.

If there is B+ then the NPN resistor is blown in the AAM.
 

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DrX said it was slot 86 but it was probably a typo.
Agree that slot 86 should normally be ground, but according to OP he tested it and found it to be same voltage as battery positive. (Maybe a typo by the OP)
 

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Agree that slot 86 should normally be ground, but according to OP he tested it and found it to be same voltage as battery positive. (Maybe a typo by the OP)
Maybe it's because of his uni internet paragraph.
 

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Discussion Starter #13
Hi DrX
Thanks for your response. I just retested relay K12 terminal #86 with multimeter set to ohms /continuity .I first test it between firewall ground strap / bolt to #86 and found open ground. Then I test it between fuse box ground stud 31 and #86 and found open ground/open circuit. I then proceed to to do what 43sqd recommend .See following post.
 

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Discussion Starter #14
Hi 43sqd
Thanks for your response. I first test circuit 15 stud on fuse box with key in second position and found 7.3 MV .Second I test slot #85 of the relay K12 with key in second position and found 0 volts. Third I test fuse panel ground stud #31 and found good ground. Forth I test circuit 15 stud on fuse panel between ground stud #31 and circuit 15 stud and found 6.0 MV while key in second position. Fifth I test C/D pink wire # 6 with key in second position and found 12.26 volts. I then wanted to test pink wire #12 & #10 for power ,as I pushed my positive test lead point in pink wire #12 while terminal plug still attached fuse board . I heard a noise and car's electrical started to work. I then test circuit 15 stud and found 12 volts.I then test slot #85 of relay K12 and found 12 volts. Do you think something is loose or crack in fuse broad and should i replace it or is there a way to open it up and check interior connections? Car is now turning on with no problems and everything is back to normal.
 

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Unlike many members here, I don't have a degree in EE, but the following sentence means nothing to me:
Then I test it between fuse box ground stud 31 and #86 and found open ground/open circuit.
Please rephrase it.
1. Terminal 86 has continuity with stud 31. (Closed circuit) OR
2. Terminal 86 and stud 31 are open circuit.

While I'm glad your ML is running again, you need to find and fix this fault unless you want to end up stranded again.
 

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Discussion Starter #16
Hi DrX
Terminal 86 and stud 31 open circuit before car turn on. Now that car is running terminal 86 has continuity with stud 31 ( closed circuit). I am going to check fuse board for cracks and plug terminals for tightness.Do you know if anyone else has had problems with fuse board and can it be disassemble .I will post my results.I don't want to get stranded again. Thanks for your help.
 

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2002 ML320, 2003 A160, 2002 ML500, 2018 GLS350d
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Thanks for clarifying. Yes, other owners have had faulty fuse panels. I recommend that you replace it. Used will suffice, also available new.

6-7 mV suggests a broken wire or corroded connector.
 

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Remove the C/D connector and check to see if pin #6 is blackened or is very loose. There should be only minimal looseness with all pins.
 

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Discussion Starter #19
Well I finally found out what was causing car to shut down .It was the ignition switch. Just changed it and car seems to be back to normal.
 

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I'm curious did you carry a lot of keys on the key ring to your ML? That seems to be the most common cause of ignition failure you describe. Congrats on your fix.
 
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